Power switches are conventionally used to couple a load with a supply voltage. In recent years, “smart” power switch devices have been developed which are equipped with one or more diagnostic abilities and protection features, for example against overload and short circuit events. For example, in such power switch devices as a power switch a MOS transistor may be used, and the switch may be opened (i.e. caused to be non-conducting between terminals of the switch) in case of overload or short circuit events.
Power switch devices may comprise one or more control terminals. One of such control terminals may for example control opening and closing of the power switch. Another one of the control terminals may for example serve to set a desired mode (for example to enable a diagnosis mode).
Power switch devices may comprise diagnosis functions, for example to detect fault conditions like overcurrent, overvoltage, overheating or a broken load. In case such a fault condition is detected, a fault signal (for example a fault current) may be output to signal fault conditions to other entities, for example to other entities in a system including the power switch.
However, for example a faulty connection to the above-mentioned control inputs may cause a misinterpretation of such a fault signal or other signal output. For example, when a connection to a control input usable to set the power switch to a diagnosis mode is broken, another entity may erroneously believe that the power switch is set to a diagnosis mode, while it is still a normal operation, and may misinterpret signals output accordingly.